The Fluent-based Reynolds stress model was applied to simulate the hydraulic characteristics of steady uniform flow in channels with partial ice cover in terms of streamwise velocity, secondary flow, Reynolds stress, and turbulent kinetic energy. The simulated results show that the formation of border ice results in the redistribution of under-ice flow on the cross section, the velocity increases in the open-water subsection, but decreases in the under-ice subsection. The resulting lateral momentum transfer produces a complex secondary flow structure, the shape, number, size and location of the vortices vary with the coverage of ice cover. The distribution of Reynolds stress is complex with negative value in the near-cover region of the under-ice subsection, and the negative region is closely related to the ice coverage, which forms a convex shape towards the open-water subsection. The differences in the roughness of ice cover, bed and side-wall result in the variation of turbulent kinetic energy in the cross section. The turbulent kinetic energy is larger in the under-ice subsection than that in the open-water subsection, indicating that the formation of border ice has complicated effects on the turbulence structure of the under-ice flow.